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Novel mesoporous 0.25Cr2O3–0.75ZrO2nanomaterials were successfully synthesized via hydrothermal method in the presence of anionic, cationic and non-ionic surfactants, namely, SDS, CTAB and Triton X-100, respectively. The effect of different surfactants and their concentrations on the physicochemical properties and the catalytic activity of the catalysts were studied by the XRD, HR-TEM, FT-IR, BET, UV–vis/DR, NH3-TPD and ethanol oxidation techniques. XRD results indicated that all the as-prepared nanomaterials were amorphous materials. The morphology study demonstrated that the sample with CTAB has the smallest particle size while that with SDS has the largest value. The catalysts prepared with non-ionic and cationic surfactants have the highest surface area and the pore volume while those prepared with anionic or without surfactant have the smallest values. Additionally, the surface area of the catalysts decreases with increasing the surfactant content. The optical study indicated that the absorption peak of the nanomaterials shifts towards the short wavelength by changing the various surfactants. It is well-observed by NH3-TPD that the non-ionic and cationic surfactants enhanced the amount of acidic sites on the catalyst surface. These results indicate that the catalytic activity of mesoporous catalysts can be improved effectively by the addition of non-ionic and cationic surfactants.

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Keggin heteropolyacids were immobilized on functionalized silica as their onium (γ-propyl-N-pyridinium, γ-propyl-N-methyl and γ-propyl-N-butyl-imidazolium) salts. Interaction between HPA and the surface-grafted onium cations affords acid salts. In contrast to bare silica, impregnated with HPA, these materials have monoanionic dispersions of HPA on the surface and superior resistance to HPA leaching in polar media. The greatest stability of the Keggin structure and resistance to leaching were found for H4SiW12O40-(SiW)-, and the lowest for H3PMo12O40-(PMo)-based samples. In the two model reactions tested, the liquid-phase synthesis of ETBE and the esterification of AcOH with EtOH, these solids display good catalytic performance (activity per anion, up to 150 and 25 h-1, respectively) and relative high structural stability. Catalysts having a greater coverage of organic functions (revealed by comparing two pyridinium salts) and hydrophobic cations (by comparing two imidazolium salts) have the best performance. Amongst the heteropolyacids studied, H4SiW12O40 is the most active and promising for catalyst design.

Magnetic resonance imaging (MRI) with the use of hyperpolarized gases as contrast agents provides valuable information on lungs structure and function. While the technology of 129Xe hyperpolarization for clinical MRI research is well developed, it requires the expensive equipment for production and detection of hyperpolarized 129Xe. Herein we present the 1H hyperpolarization of diethyl ether vapor that can be imaged on any clinical MRI scanner. 1H nuclear spin polarization of up to 1.3 % was achieved using heterogeneous hydrogenation of ethyl vinyl ether with parahydrogen over Rh/TiO2 catalyst. Liquefaction of diethyl ether vapor proceeds with partial preservation of hyperpolarization and prolongs its lifetime by ≈10 times. The proof-of-principle 2D 1H MRI of hyperpolarized diethyl ether was demonstrated with 0.1×1.1 mm2 spatial and 120 ms temporal resolution. The long history of use of diethyl ether for anesthesia is expected to facilitate the clinical translation of the presented approach.

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A SiO2-attached one-atomic layer amorphous niobium-oxide catalyst was prepared by the two-stage attaching reaction between silanol groups and Nb(OC2H5)5 followed by chemical treatments with H2O and O2.The one-atomiclayer Nb oxide catalyst was found to be active and selective for ethene formation from ethanol.

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The liquid-phase dehydration of ethanol to diethylether over heterogeneous sulfonic-acid catalysts was carried out in a stirred batch reactor. The different Amberlyst catalysts were found to have similar activities for this reaction; even though Amberlyst 70 showed a lower acid capacity compensated by a higher specific activity. By comparing the conversion of ethanol as a function of reaction mixture composition, it was found that reaction rates greatly depended on ethanol concentration but also on reaction mixture polarity. The swelling of the used resins could not explain the observed variations of initial reaction rate since this effect was observed both with resins and with homogeneous catalyst, i.e. p-toluenesulfonic acid. The initial ethanol concentration has a complex effect on initial reaction rates that could not be correlated by usual kinetic models. Taking account of the intrinsic reactivity trends of the SN2 etherification reaction, a strong dependence was found between solvent properties and initial reaction rate.

The catalytic conversion of a mixture of ethanol and glycerol over the Re - W/Al2O3 catalysts was studied. The Re - W binary system exhibits a non-additive cocatalytic effect in the conversion of ethanol and its mixture with glycerol into the fraction of olefins C4 - C9. The non-additive increase in the catalytic activity is associated with the specific structure of the binuclear metallocomplex precursors, due to which the supported metals are arranged in the immediate vicinity from each other on the support surface and intensively interact to form Re7+. The study of the combined conversion of ethanol and glycerol made it possible to find an optimum ratio of the reactants in the initial mixture. The yield of target hydrocarbons attains 50 wt.% based on the amount of carbon passed through the reactor.

The pure and palladium doped 12-tungstophosphoric acid - H3PW12O40 (HPW) and its cesium salts CsxH3-xPW12O40 (x = 1, 2, 2.25 and 2.5) were prepared and characterized by thermal analysis, FTIR, XRD, BET and XPS methods. In this paper were determined the optimal reaction temperature and the effect of palladium on the coke content during the dehydration of ethanol in the temperature range of 200?350 °C. Above 300 °C, a strong deactivation of the catalysts was caused by coke formation. The catalytic tests demonstrate that by supporting the HPW and PdyPW (y = 0.15, 0.2 and 0.25) on mesoporous molecular sieve SBA-15 the catalytic activity in ethanol dehydration reaction was improved. Palladium doping of HPW/SBA-15 significantly decreases the formation of coke deposit. The formation of coke during the ethanol dehydration does not affect the Keggin structure which led us to conclude that such catalysts can be regenerated in air and regain their catalytic activity for a short time.

Acid-supporting hollow microspheres were successfully prepared through a novel synthetic procedure on the introduction of a catalytic active species in the void space; one-pot synthesis was achieved by addition of 12-tungstophosphoric acid to the aqueous phase in a water-in-oil emulsion and simultaneous formation of a polyorganosiloxane shell (precursors are in oil phase) through sol-gel reactions. The resulting solid was porous and was active as solid-acid catalyst as shown by vapor-phase dehydration of ethanol. Copyright

Proton-free, alkali-containing layered metal oxides are thermally stable compared to their protonic counterparts, potentially allowing catalysis by Lewis acid sites at elevated temperatures. However, the Lewis acidic nature of these materials has not been well explored, as alkali ions are generally considered to promote basic but to suppress acidic character. Here, we report a rare example of an unusually acidic cesium-containing oxide CsxTi2-yMyO4 (x = 0.67 or 0.70; M = Ti vacancy or Zn). These lepidocrocite-type microcrystals desorbed NH3 at >400 °C with a total acidity of 410 μmol g-1 at a specific surface area of only 5 m2 g-1, without the need for lengthy proton-ion exchange, pillaring, delamination, or restacking. The soft and easily polarized Cs+ ion essentially drives the formation of the Lewis acidic site on the surfaces as suggested by IR of sorbed pyridine. The two-dimensional layered structure was preserved after the oxide was employed in the ethanol conversion at 380 °C, the temperature at which the protonic form could have converted to anatase. The structure was also retained after the NH3 temperature-programmed desorption measurement up to 700 °C. The production of ethylene from ethanol, well-known to occur over acid sites, unambiguously confirmed the acidic nature of this cesium titanate.

New Nb dimers on an SiO2 surface, prepared from the reaction between 5-C6H5)H-μ-(η5,η1-C5H4)>2 and surface OH groups, are found to have an oxygen-bridged dimeric structure, as characterised by extended X-ray fine structure (EXAFS), which is active and selective for the dehydratation of ethanol in contrast to the dehydrogenation ability of the Nb monomer catalyst.

Conversion of ethanol was investigated over four commercial aluminas prepared by different industrial procedures and one commercial silica-alumina. Characterization was performed by TEM, XRD, SBET and porosity measurements, and IR spectroscopy of the surface OH groups and of adsorbed CO and pyridine. Different features are attributed to different phases (γ-, δ-, θ-Al2O3) and different impurities (Na +, Cl-). Total conversion of ethanol with >99% selectivity to ethylene is achieved at 623 K over the purer Al2O 3 catalyst (Na 3+ sites in a tetrahedral environment located on edges and corners of the nanocrystals. Ethanol adsorbs dissociatively on Lewis acid-base pair sites but may also displace water and/or hydroxyl groups from Lewis acidic Al3+ sites forming the active intermediate ethoxy species. Surface ethoxy groups are supposed to be intermediate species for both diethyl ether and ethylene production. Silica-alumina also works as a Lewis acid catalyst. The slightly lower activity on surface area basis of silica-alumina than aluminas attributed to the lower density of Lewis acid sites and the absence of significant basicity.

This article analyses the role of gold nanoparticles supported on TiO2 for the gas-phase ethanol condensation. Previously, the original P25 surface was modified for increasing the Au-Ti interaction, in order to minimize the thermal deactivation. Catalysts were tested both in absence and presence of hydrogen (523–673 K, WHSV = 7.9 h?1; yEtOH= 0.32; yH2= 0-0.1; 0.1 MPa). Parent TiO2 is mainly selective for dehydration reactions yielding diethyl ether (favoured at low temperatures) and ethylene (favoured at higher temperatures). The presence of Au in the catalyst promotes dehydrogenation pathways, yielding acetaldehyde, as well as condensation products (mainly butanol, with selectivities close to 10%). According to DRIFT spectroscopy results, the strong ethanol adsorption on the TiO2 surface justifies the low yields and the high relevance of side-reactions produced by inter- or intra- molecular dehydration routes (diethyl ether, and ethylene formation). The gold addition minimizes this adsorption and enhances the main route by a double role: an improvement in the dehydrogenation rate (yielding more acetaldehyde) and an enhancement in the hydrogenation steps.

In this paper synthesis and catalytic properties of new catalysts based on double lithium-zirconium phosphate (LiZr2(PO4)3) with monoclinic NASICON-type structure, doped by indium, niobium and molybdenum are discussed. The obtained samples with particle size of 50-300 nm were characterized by X-ray diffraction, scanning electron microscopy and X-ray microanalysis. The synthesized samples exhibit catalytic activity in the dehydration and dehydrogenation reactions of ethanol conversion. The main products were acetaldehyde, diethyl ether, hydrogen, C2- and C4-hydrocarbons. Indium- and molibdenum-doped samples were characterized by high activity in dehydrogenation processes, while niobium-doped was more active in dehydration processes. The highest selectivity in diethyl ether formation was achieved for LiZr2(PO4)3 and Nb-doped samples (90 and 60% at 300°C). The highest hydrogen yield (up to 60%) was obtained with the use of In-doped catalyst. LiZr2(PO4)3 and Mo-doped samples are also noticeable for high C4-hydrocarbons formation, selectivity to which reaches 60% at 390°C. Use of a 100% hydrogen selective palladium-ruthenium alloy membrane increases hydrogen yield by 20%.

MIL-101(Cr) with adjustable Br?nsted acid density was prepared via post-synthetic sulfation strategy, which was carried out with sulfuric acid in the presence of trifluoromethanesulfonic anhydride, using nitromethane as solvent. XRD, TG, EDS, XPS, IR, NH3-TPD and acid-base titration were used to characterize structure and acidity. Adopting conversion of ethanol as a probe reaction, gas-solid catalytic characteristics on MIL-101(Cr) and post-synthetic sulfated MIL-101(Cr) in a micro fixed-bed reactor were studied by continuous feeding. Combined with the regulation of reaction parameters, selective production of ethylene (100 %) or diethyl ether (99 %) could be achieved.

Nanosize homogenous rod-like tungsten bronze CsxWO3 with excellent NIR shielding ability was successfully synthesized by a novel and facile water controlled-release solvothermal process (WCRSP).

Catalytic materials are important in industrial chemistry; these materials must be inexpensive and easy to process as well as resistant to chemicals, heat and structural loads. Poly (p-phenylene sulfide) (PPS) is a widely used and exceptionally resistant thermoplast. We demonstrate that the superficial regions of polymerized bulk PPS can be sulfonated using either SO3 or acetyl sulfate, yielding a solid core of unaltered PPS with a sulfonic acid-functionalized surface. The SO3 method was the most efficient and achieved 0.9 mmol H+ per gram of polymer. We show that the sulfonated surfaces function as durable solid acid catalysts for the dehydration of ethanol to diethyl ether. We also develop a simple method for the formation of porous PPS structures based on compression molding and porogen leaching. Based on these results, we suggest that surface functionalization of bulk PPS can be used to develop a novel class of moldable, easily produced and durable heterogeneous catalysts.

The selective dehydration of 80% ethanol to diethyl ether on copper and cerium phosphotungstates supported on MCM-41 was carried out; the latter showed higher activity.

Zeolite reactivity depends on the solvating environments of their micropores and the proximity of their Br?nsted acid sites. Turnover rates (per H+) for methanol and ethanol dehydration increase with the fraction of H+ sites sharing six-membered rings of chabazite (CHA) zeolites. Density functional theory (DFT) shows that activation barriers vary widely with the number and arrangement of Al (1–5 per 36 T-site unit cell), but cannot be described solely by Al–Al distance or density. Certain Al distributions yield rigid arrangements of anionic charge that stabilize cationic intermediates and transition states via H-bonding to decrease barriers. This is a key feature of acid catalysis in zeolite solvents, which lack the isotropy of liquid solvents. The sensitivity of polar transition states to specific arrangements of charge in their solvating environments and the ability to position such charges in zeolite lattices with increasing precision herald rich catalytic diversity among zeolites of varying Al arrangement.

A rapid and sensitive method for quantifying iodine in intact starch granules using gas chromatography is described with detection limits as low as 0.2% (w/w) iodine in starch. Sample preparation includes NaBH4 reduction of the various iodine species associated with starch to the colorless soluble iodide ion, followed by its quantitative derivatization to EtI using Et3O+BF4- in CH2Cl2. Identification and quantification of EtI is carried out by extraction and injection of the EtI so generated in CH2Cl2 into a gas chromatography-mass spectrometer (GC-MS). Routine quantification of EtI was then performed using GC with a flame ionization detector (GC-FID). Results for different iodine:potassium iodide ratios of the initially bound iodine and for seven different starch matrices showed that in all cases regression coefficients for the standards were high (R2 >0.96).

Commercial silica-alumina catalysts prepared by different procedures have been characterized. Both present strong Lewis acidity together with Br?nsted sites able to protonate pyridine. No evidence of "zeolitic" bridging OH's but significant heterogeneity of terminal silanol groups, part of which are likely "pseudobridging", was found. Similar high activity in ethanol conversion but markedly different selectivities to ethylene and diethyl ether were found. They are less active than both zeolites and γ-Al2O3. Lewis sites with alumina-like acidobasic neighbor are more selective for ethylene production while Lewis sites with silica-like covalent neighbor are more selective for diethyl ether.

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Results are presented concerning the behavior of alumina-supported gold catalysts and the effects of addition of Li2O and CeOx on the oxidation, dehydrogenation and dehydration reactions of ethanol. Pure alumina mainly acts as an acidic catalyst and produces diethyl ether and ethylene. Gold particles play an important role in converting ethanol into ethylene oxide and acetaldehyde. Addition of Li2O influences the selectivity by suppressing the formation of diethyl ether and ethylene. With the Au/Li2O/Al2O3 catalysts, a high selectivity toward ethylene oxide can be obtained. The influence of the oxygen concentration on the gas flow is investigated. It is suggested that at low concentrations, the role of oxygen is mainly to prevent coke formation on the catalytic surface.

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Steady state kinetics and measured pyridine inhibition of ethanol dehydration and dehydrogenation rates on γ-alumina above 623 K show that ethanol dehydrogenation can be described with an indirect hydrogen transfer mechanism to form acetaldehyde and ethane and that this mechanism proceeds through a shared surface intermediate with ethylene synthesis from ethanol dehydration. Ethane is produced at a rate within experimental error of acetaldehyde production, demonstrating that ethane is a coproduct of acetaldehyde synthesis from ethanol dehydrogenation. Steady state kinetic measurements indicate that acetaldehyde synthesis rates above 623 K are independent of co-fed water partial pressure up to 1.7 kPa and possess an ethanol partial pressure dependence between 0 and 1 (Pethanol = 1.0-16.2 kPa), consistent with ethanol dehydrogenation rates being inhibited only by ethanol monomer surface species. The surface density of catalytically active sites for ethylene and diethyl ether production were estimated from in situ pyridine titration experiments to be ～0.2 and ～1.8 sites nm-2, respectively, at 623 K. Primary kinetic isotope effects for ethylene and acetaldehyde are measured only when the C-H bonds of ethanol are deuterated, verifying that C-H bond cleavage is kinetically limiting for both products. The proposed indirect hydrogen transfer model for acetaldehyde synthesis is consistent with experimentally observed reaction rate dependences and kinetic isotope effects and highlights the complementary role of hydrogen adatom removal pathways in the formation of aldehydes on Lewis acidic systems. (Chemical Equation Presented).

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Al-FSM-16 mesoporous silicas were synthesized either by direct method, from Al-kanemite (Al-FSM-16/D), or by post-synthesis impregnation of purely siliceous FSM-16 with Al(NO3)3 (Al-FSM-16/P) and characterized with XRD, XRF, SEM, TEM, nitrogen sorption isotherms, 27Al and 29Si MAS NMR, FTIR, XPS, NH3-TPD, FTIR of pyridine adsorption and catalytic decomposition of ethanol. Only substitutional Al sites exist in Al-FSM-16/D, while in Al-FSM-16/P some Al remains in extra-lattice positions. Upon transformation of Al-FSM-16/D into hydrogen form a certain amount of extra-framework Al is formed. Direct alumination introduces a higher degree of structural disorder. In Al-FSM-16/D, Al is preferentially accumulated at inner pore walls, while in Al-FSM-16/P external surface is Al-rich. Post-synthesis alumination is more efficient in introducing acid sites into FSM-16. The generated acidity is of Br?nsted and Lewis nature, the latter being stronger than the former.

The phase transformations of platelet- and rod-shaped γ-Al2O3 were investigated and compared to that of a commercial sample by XRD, BET surface area measurements, transmission electron microscopy (TEM), solid state 27Al-NMR, and ethanol temperature programmed desorption (TPD) after sequential annealing in air up to 1100 °C. After annealing at 1100 °C, commercial γ-Al2O3 mostly transformed into α-Al2O3 with drastic surface area reduction (from 200 m2/g to 25 m2/g). Interestingly, platelet- and rod-shaped γ-Al2O3 which showed exactly the same XRD patterns transformed into different phases upon the high temperature calcinations. Platelet-shaped γ-Al2O3 transformed into θ-phase while the rod-shaped γ-Al2O3 transformed into the δ-phase and not to the α-polymorph. Both platelet- and rod-shaped aluminas retained significantly higher surface area (～60 m2/g) than the commercial one after the same treatment at 1100 °C. These results suggest that the phase transformation in γ-Al2O3 is strongly affected by not only the crystal structure of the starting material, but its morphology as well. Ethanol TPD from platelet- and rod-shaped alumina after 1100 °C annealing, showed significantly different desorption profiles which suggest different surface characteristics even though they had almost the same surface areas. These different phase transformations were also supported by solid state 27Al-NMR. After 1100 °C annealing commercial alumina showed the presence of mostly octahedral Al3+ ions, but the other two samples displayed even higher number of tetrahedral Al3+ ions than the initial γ-Al2O3. Morphological changes were also confirmed by TEM. All these results consistently suggest the morphology-dependent phase transformations of γ-Al2O3 and the improved thermal stability of platelet- and rod-shaped γ-Al2O3 in comparison to a commercial γ-Al2O3.

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The aim of present work was to evaluate a role of the secondary structures of the K2HPW12O40 and K2.5H 0.5PW12O40 salts in their catalytic activity for vapour-phase dehydration of ethanol. Particular attention was directed to the role of H3PW12O40 (HPW) existing as a self-organized surface layer, which covers partially or entirely the K 3PW12O40 core. The results showed that both salts are much more active than bulk HPW. It turned out that the dehydrated protons present in the studied salts transform ethanol to ethylene much easier than the hydrated protons existing in the HPW. The ammonia sorption measurements demonstrated that the [N2H7]+ adducts were formed easier on the surface of the K2HPW12O40 salt whereas the formation of the NH4+ cations dominated in the bulk HPW. The structures of potassium tungstophosphates after catalytic reaction were investigated by the FT-IR, XRD and N2-sorption methods. A self-organized surface layer of HPW in the K2HPW12O 40 salt was unstable because it transformed to the crystalline HPW, due to the reaction temperature as well as to the presence of ethanol or water (dehydration product). However, the structure of the K2HPW 12O40 salt can be partially restored after ageing for a month at ambient temperature in air with the relative humidity of 25%. In contrast, the secondary structure of the K2.5H0.5PW 12O40 salt remained practically unchanged after catalytic reaction. It makes this salt a very promising catalyst for the ethanol dehydration, with the conversion of 99.4% and the selectivity to ethylene attaining ca. 100% at 448 K.

Isothermal anaerobic titration with ethanol as a probe molecule is proposed as an accurate technique to quantify active redox site densities in supported metal oxide catalysts. It is shown that the number of active redox sites for VOx-Al2O3, MoOx-Al2O3, and WOx-Al2O3 catalysts is a function of both the metal atom and its oxide surface density, but the intrinsic redox rate per active site is independent of both of these factors. Thus, the difference in steady-state redox rates per metal atom is due only to differences in the number of redox sites under reaction conditions.

The low-temperature dehydration of bioethanol is an environmentally benign route to ethene production. Here we compare the catalytic properties of a series of cage-based small-pore zeolites with different framework structures, acid strengths, and/or crystallite sizes for ethanol dehydration at 200 8C under wet conditions (H2 O/EtOH = 0.2). Among the zeolites studied here, nanocrystalline H-RTH was found to be considerably more effective than H-mordenite, the best catalyst for this reaction known to date, which can be rationalized by product shape selectivity. Whereas the acidity of this zeolite also plays a crucial role in selectively forming ethene, its nanocrystallinity is primarily responsible for the observed high catalyst durability.

Dehydration of MeOH to dimethyl ether and EtOH to diethyl ether and ethene was studied at the gas-solid interface in the presence of bulk and SiO2-supported Keggin heteropoly acids (HPAs) H3PW12O40 (PW) and H4SiW12O40 (SiW) as catalysts. The catalysts were prepared by HPA impregnation from water and MeOH. Their acid strength, texture and structural integrity was characterised using NH3 adsorption calorimetry, BET, XRD and DRIFT spectroscopy. The strength of acid sites in HPA/SiO2 catalysts increased monotonously with HPA loading. In the dehydration of MeOH and EtOH, the turnover reaction rate for PW catalysts was higher than for SiW catalysts in agreement with their acid strength. HPA catalysts prepared from water and MeOH had a very close acid strength and showed similar activities in alcohol dehydration. The steady-state catalyst activity was found to correlate with the density of catalyst proton surface sites rather than with the HPA loading. This indicates that alcohol dehydration occurred via a mechanism of surface-type HPA catalysis at the gas-solid interface rather than a bulk-type (pseudo-homogeneous) catalysis.

Sulfated zirconia ceramic foams were produced by the sol-gel process using air-liquid foam and surfactants as dual pore templates. The results showed the presence of high porosity (until 93%) and surface area (105 m2 g-1), and a hierarchical structure of pore sizes in the range of macro (between 10 and 76 μm), and meso-scales (?6 nm). The hierarchical porous structure and pore wall texturization of ceramic foams produced by this process, besides the presence of strong acid sites, certify these materials as heterogeneous catalysts for dehydration reactions.

The nature of acidic sites on layered zirconium phosphite has been characterized by IR spectra, thermal analysis and catalytic dehydration of ethanol.The catalytic behaviour was compared with that of α-zirconium phosphate.The reaction sequences for ether and ethen formation were studied by analysing the kinetic data.The Broensted acidity of monohydrogen orthophosphate groups was considered to be the common active site on α-zirconium phosphate and the zirconium phosphite sample calcined at 673 K.For the latter compound, the phosphite groups on the exterior surface were found to be oxidised to phosphate by calcination in air.The uncalcined sample of zirconium phosphite exhibited a different catalytic behaviour.Its selectivity for diethyl ether was the highest among the catalysts studied.The dehydration activity of this compound was presumed to be due to the polar P-H bonds in the phosphite groups.

We report the dehydrogenative synthesis of esters from enol ethers using water as the formal oxidant, catalyzed by a newly developed ruthenium acridine-based PNP(Ph)-type complex. Mechanistic experiments and density functional theory (DFT) studies suggest that an inner-sphere stepwise coupled reaction pathway is operational instead of a more intuitive outer-sphere tandem hydration-dehydrogenation pathway.

Abstract—: We have studied the catalytic activity of LiZr2(PO4)3-based NASICON-type phosphates for conversion of C2 and C3 aliphatic alcohols with the aim of selectively preparing C2–C4 olefins. Selectivity has been controlled via partial heterovalent substitutions of In3+ or Nb5+ for Zr4+ or Mo for phosphorus. We have investigated the structure and morphology of the synthesized catalysts. The nature of the dopants has been shown to play a key role in determining the selectivity of the catalysts studied. Partial In3+ substitution for Zr4+ improves the dehydrogenating properties of the materials, whereas partial substitutions of Nb5+ for Zr4+ and Mo6+ for P5+ improve their dehydrating properties. We have demonstrated the possibility of highly selective preparation of ethylene and butylenes from ethanol and of propylene from propanol-1 and propanol-2.

The selective production of C3+olefins from renewable feedstocks, especially via C1and C2platform chemicals, is a critical challenge for obtaining economically viable low-carbon middle-distillate transportation fuels (i.e., jet and diesel). Here, we report a multifunctional catalyst system composed of Zn-Y/Beta and “single-atom” alloy (SAA) Pt-Cu/Al2O3, which selectively catalyzes ethanol-to-olefin (C3+, ETO) valorization in the absence of cofed hydrogen, forming butenes as the primary olefin products. Beta zeolites containing predominately isolated Zn and Y metal sites catalyze ethanol upgrading steps (588 K, 3.1 kPa ethanol, ambient pressure) regardless of cofed hydrogen partial pressure (0-98.3 kPa H2), forming butadiene as the primary product (60% selectivity at an 87% conversion). The Zn-Y/Beta catalyst possesses site-isolated Zn and Y Lewis acid sites (at ～7 wt % Y) and Br?nsted acidic Y sites, the latter of which have been previously uncharacterized. A secondary bed of SAA Pt-Cu/Al2O3selectively hydrogenates butadiene to butene isomers at a consistent reaction temperature using hydrogen generatedin situfrom ethanol to butadiene (ETB) conversion. This unique hydrogenation reactivity at near-stoichiometric hydrogen and butadiene partial pressures is not observed over monometallic Pt or Cu catalysts, highlighting these operating conditions as a critical SAA catalyst application area for conjugated diene selective hydrogenation at high reaction temperatures (>573 K) and low H2/diene ratios (e.g., 1:1). Single-bed steady-state selective hydrogenation rates, associated apparent hydrogen and butadiene reaction orders, and density functional theory (DFT) calculations of the Horiuti-Polanyi reaction mechanisms indicate that the unique butadiene selective hydrogenation reactivity over SAA Pt-Cu/Al2O3reflects lower hydrogen scission barriers relative to monometallic Cu surfaces and limited butene binding energies relative to monometallic Pt surfaces. DFT calculations further indicate the preferential desorption of butene isomers over SAA Pt-Cu(111) and Cu(111) surfaces, while Pt(111) surfaces favor subsequent butene hydrogenation reactions to form butane over butene desorption events. Under operating conditions without hydrogen cofeeding, this combination of Zn-Y/Beta and SAA Pt-Cu catalysts can selectively form butenes (65% butenes, 78% C3+selectivity at 94% conversion) and avoid butane formation using onlyin situ-generated hydrogen, avoiding costly hydrogen cofeeding requirements that hinder many renewable energy processes.

Simple and economical conversion of aqueous ethanol feed streams into butenes by a single step method using transition metal oxides on a silica supports under preselected processing conditions. By directly producing a C4-rich olefin mixture from an ethanol containing stream various advantages are presented including, but not limited to, significant cost reduction in capital expenses and operational expenses.

"Frustrated Lewis pairs"(FLPs) continue to exhibit unique reactivity for the reduction of organic substrates, yet to date, the catalytic hydrogenation of an ester functionality has not been demonstrated. Here, we report that iPr3SnNTf2 (1-NTf2; Tf = SO2CF3) is a more potent Lewis acid than the previously studied iPr3SnOTf; in an FLP with 2,4,6-collidine/2,6-lutidine (col/lut), this translates to faster H2 activation and the catalytic hydrogenolysis of an ester bond by a main-group compound, furnishing alcohol and ether (minor) products. The reaction outcome is sensitive to the steric and electronic properties of the substrate; CF3CO2Et and simple formates (HCO2Me and HCO2Et) are catalytically reduced, whereas related esters CF3CO2nBu and CH3CO2Et show only stoichiometric reactivity. A computational case study on the hydrogenation of CF3CO2Et and CH3CO2Et reveals that both share a common mechanistic pathway; however, key differences in the energies of a Sn-acetal intermediate and transition states emerge, favoring CF3CO2Et reduction. The alcohol products reversibly inhibit 1-NTf2/lut via formation of resting-state species 1-OR/[1·(1-OR)]+[NTf2]- however, the extra energy required to regenerate 1-NTf2/lut exacerbates the unfavorable reduction energy profile for CH3CO2Et, ultimately preventing turnover. These findings will assist the design of future main-group catalysts for ester hydrogenation, with improved performance.

Here, we study the influence of the Cu modified (Zr + Ce)O2-Al2O3 systems composition and synthesis conditions on their catalytic properties in the ethanol conversion. First, we obtained varios ratios mixed Al-Zr supports at different synthesis temperatures using a sol-gel method. Then we modified the surface of the oxides by Cu, reduced in hydrogen flow. All obtained systems demonstrated а high alcohol conversion and selectivity to acetaldehyde. The surface area (SBET), the pore volume, and the pore distribution were measured by the nitrogen adsorption method. The structure of the samples have been investigated by XRD and XAS-spectroscopy. A correlation between the synthesis temperature and contents of mixed oxide support and textural properties were observed. The results show that Al-Zr mixed oxide support structure plays a crucial role in forming a Cu active site for ethanol dehydrogenation to acetaldehyde.

Aliphatic alcohols C1–C4 can serve as raw material for the production of essential organic products, such as olefins, aldehydes, ketones and ethers. For the development of catalysts of alcohols’ conversion, the authors considered two families of framework phosphate compounds with significant chemical, thermal and phase stability: NaZr2(PO4)3 (NZP/NASICON) and Sc2(WO4)3 (SW). Variation in the composition of zirconium-containing NZP- and SW-complex phosphates allows one to vary the number and strength of Lewis acid centers and incorporate oxidative-reducing centers (such as d-transition metals) into the structure. The phosphates M0.5+xNixZr2 ? x(PO4)3 (where M are Mn and Ca) were studied in the reactions of ethanol conversion. From the results of complex investigation, the compounds with M–Mn (x = 0, 0.3 and 0.5) were crystallized in the SW-type (monoclinic symmetry), while the phosphates with M–Ca (x = 0, 0.2 and 0.4) were characterized as the NZP-structured compounds (trigonal symmetry). The surface areas and pore volumes of synthesized catalysts varied, with different compositions, from 14 to 32?m2/g and 0.03 to 0.12?mL/g, respectively. From the catalytic experiments, the main direction of conversion on all the studied catalysts was ethanol dehydrogenization with acetaldehyde formation. The other conversion products—diethyl ether and ethylene—were produced with small yields. Based on the results obtained, the NZP-sample Ca0.5Zr2(PO4)3 can be considered as a selective catalyst for producing acetaldehyde at 400?°C with a yield of 55% from its theoretical amount.

Many MRI contrast agents formed with the parahydrogen-induced polarization (PHIP) technique exhibit biocompatible profiles. In the context of respiratory imaging with inhalable molecular contrast agents, the development of nonflammable contrast agents would nonetheless be highly beneficial for the biomedical translation of this sensitive, high-throughput and affordable hyperpolarization technique. To this end, we assess the hydrogenation kinetics, the polarization levels and the lifetimes of PHIP hyperpolarized products (acids, ethers and esters) at various degrees of fluorine substitution. The results highlight important trends as a function of molecular structure that are instrumental for the design of new, safe contrast agents for in vivo imaging applications of the PHIP technique, with an emphasis on the highly volatile group of ethers used as inhalable anesthetics.

Abstract: Using a combination of physicochemical methods, such as TEM, SEM, EDS, XPS,NH3–TPD, and N2 adsorption,the study investigates the structure of a number of supports(Al2O3,SiO2, TiO2,ZrO2, and C) and of Au/support catalyst samples (Au =0.5%). The concentration of highly active 2–4 nm gold particles in Au catalystsis influenced by the support’s texture; this concentration increases in thefollowing order: Au/TiO2 2 22O3. The acidity ofAu catalysts is influenced by the support’s nature; this acidity decreases inthe following order: Al2O3 >TiO2 > ZrO2 >SiO2 >> Au/C. At 275°C, a carbon support isinactive in ethanol conversion to butanol. In the presence of oxide supports,the target reaction occurs at a relatively low rate by a bimolecular condensation mechanism. OverAu/Al2O3,Au/SiO2, Au/TiO2, orAu/ZrO2, the reaction occurs more rapidly by analdol condensation mechanism. At anethanol conversion of 14–18%, the butanol selectivity increases in the followingorder: Au/C(0) 2 (0.4%) 2 (1.5%) 2(2%) 2O3 (78%). Thehigh efficiency of Au/Al2O3 stemsfrom the high density of the Aln+–O2– sites located onthe support’s surface, and of the coordination-unsaturatedAu0(KH) atoms located on the surface of 2–4 nmgold particles. [Figure not available: see fulltext.]

Upgrading of ethanol to n-butanol through dehydrogenation coupling has received increasing attention due to the wide application of n-butanol. But the enhancement of ethanol dehydrogenation and followed coupling to produce high selectivity to n-butanol is still highly desired. Our previous work has reported an acid-base-Ag synergistic catalysis, with Ag particles supported on Mg and Al-containing layered double oxides (Ag/MgAl-LDO). Here, Ag-LDO interfaces have been manipulated for dehydrogenation coupling of ethanol to n-butanol by tailoring the size of Ag particles and the interactions between Ag and LDO. It has been revealed that increasing the population of surface Ag sites at Ag-LDO interfaces promotes not only the dehydrogenation of ethanol to acetaldehyde but also the subsequent aldol condensation of generated acetaldehyde. A selectivity of up to 76 % to n-butanol with an ethanol conversion of 44 % has been achieved on Ag/LDO with abundant interfacial Ag sites, much superior to the state-of-the-art catalysts.

Described is the transformation of ethanol into 1-butanol, acetaldehyde and other products by the Guerbet reaction (GR) over mixed metal oxides (MMOs) as catalysts. The MMOs, in which Mg2+ was partially (20 mol%) substituted by Fe2+, Co2+, Ni2+, Cu2+, and Zn2+, were obtained from hydrotalcite precursors and the reactions conducted in a fixed bed flow reactor. EPR was used to observe oxygen vacancies after the catalytic reactions, which may be related to the ethanol reactivity due to the basicity enhancement of the catalyst. Carbon deposition, mostly filamentous, was observed in all catalysts and a trend between the metal-carbon bond energy and the percentage of deposited carbon was established. This correlation and the catalyst product distribution can be useful to tailor new catalysts. Using four parameters, ethanol conversion, 1-butanol and side-product selectivities and percentage of carbon deposition, Zn20MMO proved to be the best choice for GR.

Ethanol transformation with high product selectivity is a great challenge, especially for high weight molecules. Here, we show a combination study of kinetic, thermodynamic, and in situ spectroscopy measurements to probe the selective upgrading of ethanol over lamellar Ce(OH)SO4·xH2O catalysts, with 60-70% Ce3+ preserved during the catalysis. High methyl phenols (MPs) selectivity at ～80% within condensation products was achieved at ～50% condensation yield (3.0 kPa C2H5OH, 15 kPa H2, Ar balanced, 693 K, 1 atm, gas hourly space velocity (GHSV) ～5.4 min-1), with acetaldehyde, acetone, 4-heptanone, and 2-pentanone as the key reaction intermediates. Kinetic measurements with the assistance of isotope labeling proved that MPs generated from the kinetically relevant step (KRS) of C-C bond coupling of enolate nucleophilically attacks surface C2H4O following a Langmuir-Hinshelwood model. Low ethanol and water pressures and high acetaldehyde and hydrogen pressures were proved to be favored for MPs generation rather than dehydration, in which hydrogen could reduce the amount of lattice oxygen and facilitate the preparation of MPs while water and ethanol both compete with acetaldehyde for active sites during catalysis. On the basis of in situ X-ray diffraction (XRD), quasi-in situ X-ray photoelectron spectroscopy (XPS), and Raman characterizations, the Ce(OH)SO4 crystal structure was proved to be maintained along with ethanol activation, and the Ce3+-OH Lewis acid-base pair was proved to be the active species for the selective C-C bond coupling. The KRS assumption was also supported by the apparent activation energy assessment within the reaction network on dehydration, dehydrogenation, aldol condensation, and cyclization and a series of negligible kinetic isotope effects (KIEs). This system can be easily extended to some other systems related to C-C bond coupling and is attracting attention on converting oxygenate platform molecules over lanthanide species.

A catalytic, light-promoted hydrosilylative cleavage reaction of alkyl ethers is reported. Initial studies are consistent with a mechanism involving heterolytic silane activation followed by delivery of a photohydride equivalent to a silyloxonium ion generated in situ. The catalyst resting state is a mixture of Cp*Ir(ppy)H (ppy = 2-phenylpyridine-κC,N) and a related hydride-bridged dimer. Trends in selectivity in substrate reduction are consistent with nonradical mechanisms for C-O bond scission. Irradiation of Cp*Ir(ppy)H with blue light is found to increase the rate of hydride delivery to an oxonium ion in a stoichiometric test. A comparable rate enhancement is found in carbonyl hydrosilylation catalysis, which operates through a related mechanism also involving Cp*Ir(ppy)H as the resting state.

A zinc and tantalum-containing mesoporous silica catalyst highly active and selective in the Lebedev process has been prepared using the one-pot TUD-1 methodology. Selectivity towards butadiene reached 60-70%, making Zn-Ta-TUD-1 one of the best performing catalysts in the literature. To rationalize these results and establish a structure-activity relationship, a series of similar catalysts was prepared and characterized. Nitrogen physisorption, XPS, ICP-AES, XRD, TEM, UV-vis spectroscopy, TGA NH3-TPD, H2-TPR and FT-IR techniques were used. The most active samples were found to possess a large specific surface area and highly dispersed metal oxide phase incorporated within the mesoporous silica matrix. In combination with catalytic testing, characterization also showed a direct correlation between the number of Lewis acid sites and butadiene yield, confirming the structure-activity relationship theory prevalent for the Lebedev process. Deactivation of Zn-Ta-TUD-1 was also studied using the same techniques to characterize the properties of spent catalysts. It was found that the accumulation of heavy carbonaceous species caused a reduction of specific surface area and pore size coinciding with the observed loss in activity. Nevertheless, the pores of TUD-1 were large enough to avoid total pore blockage and a high selectivity could be maintained for 72 hours.

Aluminophosphate compounds (AlPO4-5) with the AFI structure framework are important members of microporous zeolites group and molecular sieves materials because having an enormous variety of structures leading to high potential catalytic applications. AlPO4-5 molecular sieves have been prepared via the hydrothermal reaction by using triethylamine as a template. Molybdenum and zinc bimetal supported AlPO4-5 zeolite catalysts (MoZn/AlPO4-5) were prepared using a co-impregnation method with different molar ratios. The obtained samples were described by the physicochemical characterizations techniques. The bimetal ratios effect towards the dehydration of ethanol was investigated. MoZn(4)/AlPO4-5 exhibit the most active catalyst towards ethylene formation and the parent AlPO4-5 was the least active but with high selectivity towards diethyl ether production. This conversion convinced by ZnMoO4 phase formation during Mo and Zn oxides interactions leading to improving the acid sites which are a favorite environment and augment to ethylene formation.

Catalysts composed of copper supported on ZnAl2O4 were prepared by conventional impregnation of a commercial zinc aluminate powder using copper nitrate water solutions. The fresh catalysts were characterized by XRD, skeletal IR and DR-UV–vis spectroscopies, FE-SEM microscopy, BET and pore volume measurements. The catalysts were tested in the conversion of ethanol (96percent assay, 6.9percent vol in nitrogen) at GHSV 10,000 h?1. The spent catalysts were characterized by FESEM and DR-UV–vis. These catalysts are very efficient for the dehydrogenation of ethanol to acetaldehyde, with selectivities in excess of 95percent at low conversion, persisting also at total conversion, allowing yields up to 90percent. The most active species appear to be on copper metal nanoparticles grown over Zn-poor substoichiometric spinel nanoparticles. The catalysts reduce themselves on stream. The high selectivity at low temperature is in part due to the ability of copper to kill the dehydration activity of the zinc aluminate support to diethyl ether. The selectivity to acetaldehyde decreases at very high temperature (> 673 K) due to overconversion of acetaldehyde to thermodynamically more stable products such as methane, acetone, propene and carbon oxides, as well as to increased competition with the more favored dehydration reaction. IR studies show the intermediate role of surface ethoxy-groups.

ZnO-CeO2/SBA-15 catalysts were prepared by two kinds of solid-state grinding method and used for the production of 1,3-butadiene (1,3-BD) from ethanol. A mixture of SBA-15 (with or without organic template) and metal precursors were ground in solid-state. The obtained catalysts were characterized by TG, N2 adsorption-desorption, TEM, XRD, Py-FTIR and NH3-TPD techniques. Superior dispersion of metal oxides and more exposed acid sites were achieved on the catalyst 10Zn1Ce5-AS with the presence of organic template in SBA-15 during the solid-state grinding process. The catalytic performance was evaluated in a fixed-bed reactor and a 1,3-butadiene selectivity of as high as 45% is achieved. This is attributed to the coupling effect of Zn and Ce species in the mesopores of SBA-15, in which Zn promotes ethanol dehydrogenation and Ce enhances aldol-condensation, respectively. Additionally, solvent-free method inspires new catalyst synthesis strategy for the production of 1,3-butadiene from ethanol.

A simplified processes for producing desired chemicals such as butenes from feedstock mixtures containing ethanol. In one set of embodiments this is performed in a single step, wherein a feed containing ethanol in a gas phase is passed over an acidic metal oxide catalyst having a transition metal dispersion of at least 5% on a metal oxide support. The ethanol content of the feedstock mixture may vary from 10 to 100 percent of the feed and in those non-eat applications the ethanol feed may contain water.

Mesoporous MgO-SiO2 mixed oxide catalysts were prepared for the conversion of ethanol to 1,3-butadiene. Mesoporosity was obtained by using SBA-15 material as support for magnesia or by applying one-pot synthesis method wherein magnesia precurso

FUEL product additive (glycerol) solketal and acetone. can be produced This reaction through was acetalization conducted over reaction acidified of silica biodiesel derived by-from sustainable bioresource rice husk in a batch reactor under the solvent-free condition. The chemical and structural properties of the prepared catalyst were studied by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), N2 adsorption/desorption isotherms, temperature-programmed desorption of ammonia (NH3-TPD) and scanning electron microscope (SEM). Based on this paper, the optimized conditions using 15% phosphoric acid acid ifiedsilica extracted from rice huskash (10 wt.% PO4 loaded SiO2) are 50°C (lower temperature) with the molar ratio of acetone: glycerol = 2. Reusability test used to examine the stability of the catalytic activity was investigated. This effort is a serious step for development and taking apart of solketal as the main product from glycerol and acetone by using waste resources.

Catalytic behaviour of supported nanometal catalysts for alcohols selective oxidation depends on the nature of the support and its surface. To identify the main feature that could explain these effects, supported mono- (Au) and bimetallic (AuAg) catalysts were prepared by using pure MgO, ZnO and Nb2O5, representative of three different types of oxides (basic, amphoteric and acidic, respectively), to get homogeneous metal-support interaction for each catalyst. The catalysts were characterized by XRD, N2 physisorption, TEM, UV–vis, XPS and 2-propanol decomposition as test reaction. It was found that the catalytic activity is influenced by the electron mobility between the gold nanoparticles and the support, which in turns depends on the intermediate electronegativity of the support. Selectivity in n-octanol oxidation was determined by redox properties of the gold species, the acid-base properties of the supports and the catalyst pretreatment. Silver addition modified the acid-base properties of the catalytic system, thus influencing the selectivity in n-octanol oxidation. Pretreatment of the catalyst (drying in air or thermal treatment in hydrogen flow) had a significant impact on its activity and selectivity.

Mg-Zr/MFI nanosheet (NS) catalysts were prepared by a wet impregnation method for ethanol conversion to 1,3-butadiene (1,3-BD) via the two-step method in a dual fixed bed reaction system. Compared with Zr catalysts loaded on MFI(micro) or commercial SiO2, 16%Zr/MFI(NS) gave the better performance, with 42.3% 1,3-BD selectivity and 60.5% total conversion of ethanol and acetaldehyde. Introducing 1.2 wt% Mg to 16%Zr/MFI(NS) improved the 1,3-BD selectivity to 54.7% at the expense of a 6% drop in the catalytic activity. Reaction conditions imposed remarkable influence on the reaction results. When the reaction was conducted at 350 °C, a WHSV of 1.44 h-1 and a 2 : 1 ratio of ethanol to acetaldehyde, the 1,3-BD selectivity reached 74.6% with 41.5% total conversion. Such high performance over 1.2%Mg-16%Zr/MFI(NS) was maintained well in a 7 day (168 h) run without deactivation. The catalysts were characterized by XRD, N2 adsorption, UV-Vis, Raman, and infra-red spectroscopy, NH3-TPD, TEM and TG. The results showed that the Zr species on MFI(NS) are well distributed with the highest dispersion as compared with the microporous MFI and SiO2 supported Zr catalysts. The Zr species preferentially occupied the silanol nests of MFI(NS) and eliminated the Br?nsted acid sites at 4 wt% Zr loading, and afforded abundant Lewis acid sites in the form of Zr(OH)(OSi)3 when the Zr loading was increased to 16 wt%. As a base site, Mg is inactive for MPVO reduction but slightly active for the aldol condensation of acetaldehyde, both of which are much inferior to that of the Lewis acid sites. The 1.2%Mg-16%Zr/MFI(NS) catalyst with hierarchical structures of meso- and micro-pores, abundant weak Lewis acid sites but nearly no Br?nsted acid sites is competent for the two-step ethanol to 1,3-BD conversion process with high activity, selectivity and stability.

Three bidentate phosphoramidite ligands were synthesized, characterized, and employed in Rh-catalyzed hydroformylation of vinyl ethers. The complex Rh(acac)(2,2′-bis{(di[1H-indol-1-yl]phosphanyl)oxy}-1,1′-binaphthalene} (acac = acetylacetone) (Rh-L4) was also synthesized and characterized. Rh-L4 showed good regioselectivity for the hydroformylation of vinyl ethers under mild reaction conditions: 2 MPa of syngas, 1:1 (H2/CO) substrate/catalyst molar ratio 1000:1, and 60 °C. The linear selectivity was up to 98%, and in most cases was about 80%, with no hydrogenation product formation observed, which could be a potential way to synthesize 1,3-propanediol. A mechanism study including density functional theory computational analysis showed that both Rh–H and CO insertion steps in the hydroformylation of vinyl ether were linear-preferred in our catalyst system.

Novel catalytically active cationic Si(II) and Ge(II) compounds were synthesized and isolated in pure form. The Ge(II)+-based compounds proved to be stable against air and moisture and therefore can be handled very easily. All compounds efficiently catalyze the oxidative coupling of hydrosil(ox)anes with aldehydes and ketones as oxidation reagents and simultaneously the reductive ether coupling at very low amounts of 0.01 mol %. Because the catalysts also catalyze the reversible cyclotrimerization of aldehydes, paraldehyde can be used as a convenient source for acetaldehyde in siloxane coupling. It is shown that the reaction is especially suitable to make siloxane copolymers. Moreover, a new fluorine-free weakly coordinating boronate anion, B(SiCl3)4-, was successfully combined with the Si(II) and Ge(II) cations to give the stable catalytically active ion pairs Cp*Si:+B(SiCl3)4-, Cp*Ge:+B(SiCl3)4-, and [Cp(SiMe3)3Ge:+]B(SiCl3)4-.

In this article, we investigated the I2-promoted cyclic dialkyl ether formation from 6-membered oxanickelacycles originally reported by Hillhouse. A detailed mechanistic investigation based on spectroscopic and crystallographic analysis revealed that a putative reductive elimination to forge C(sp3)-OC(sp3) using I2 might not be operative. We isolated a paramagnetic bimetallic NiIII intermediate featuring a unique Ni2(OR)2 (OR = alkoxide) diamond-like core complemented by a μ-iodo bridge between the two Ni centers, which remains stable at low temperatures, thus permitting its characterization by NMR, EPR, X-ray, and HRMS. At higher temperatures (>-10 °C), such bimetallic intermediate thermally decomposes to afford large amounts of elimination products together with iodoalkanols. Observation of the latter suggests that a C(sp3)-I bond reductive elimination occurs preferentially to any other challenging C-O bond reductive elimination. Formation of cyclized THF rings is then believed to occur through cyclization of an alcohol/alkoxide to the recently forged C(sp3)-I bond. The results of this article indicate that the use of F+ oxidants permits the challenging C(sp3)-OC(sp3) bond formation at a high-valent nickel center to proceed in good yields while minimizing deleterious elimination reactions. Preliminary investigations suggest the involvement of a high-valent bimetallic NiIII intermediate which rapidly extrudes the C-O bond product at remarkably low temperatures. The new set of conditions permitted the elusive synthesis of diethyl ether through reductive elimination, a remarkable feature currently beyond the scope of Ni.

A process for producing ethylene from an ethanol feedstock comprises a step of subjecting the ethanol feedstock to a dehydration reaction in the presence of a supported heteropolyacid salt catalyst. The supported heteropolyacid salt catalyst includes a support and a heteropolyacid salt compound which is carried on the support and which is represented by a formula as defined herein.

Abstract: A study of the kinetics of ethanol conversion in the presence of Zr-containing zeolites BEA doped with palladium particles has revealed the order of formation of the main reaction products. It has been shown that the primary processes are ethanol dehydrogenation to acetaldehyde on Pd sites and ethanol dehydration to diethyl ether on the acid sites of the catalyst. After that, acetaldehyde undergoes the aldol–croton condensation reaction to form crotonal, which is hydrogenated to butanol on the metal sites. Butanol, in turn, is dehydrated into butenes, which undergo hydrogenation to butane. The presence of hydrogen in the gas phase leads to the displacement of ethanol from the metal surface and prevents the formation of surface carbonates and acetates. It has been found that hydrogen significantly accelerates ethanol dehydration owing to a decrease in the activation energy, which can be attributed to hydrogen spillover to the zeolite. The addition of water inhibits all acid-catalyzed reactions owing to competitive adsorption on acid sites and thereby decreases the butanol yield and the ethanol conversion.

Superior catalytic performances were obtained over LiZnHf-MFI zeolite nanosheets for ethanol conversion into butadiene in comparison with the microporous MFI based catalyst due to the synergistic effect of the nanosheet structure and acidic site modulatio

Operando DRIFTS is used to identify the nature and the role of the surface sites of hydroxyapatites (HAps) involved in the catalytic transformation of ethanol to n-butanol. The surface processes occurring upon a first reaction step followed by a step under He flow greatly influence the reactivity of HAps in a subsequent second reaction step. Ethanol is found to be mostly activated by the basic OH? groups of HAps, as indicated by the concomitant recovery of ethanol conversion and OH? groups under He flow. The drastic changes in selectivity observed during the second reaction step reveal the key role of acidic sites cooperatively acting with basic sites for basic reaction steps. Once the POH groups are poisoned by extensive formation of polymeric carbon species and the Ca2+ sites are available, the production of acetaldehyde is drastically promoted at the expense of that of n-butanol. It is concluded that i) acetaldehyde acts as an intermediate in the formation of n-butanol, and ii) various active sites are involved in the key basic reaction steps such as Ca2+?OH? and POH?OH? acid-base pairs in the dehydrogenation of ethanol to acetaldehyde and the aldol condensation for n-butanol formation, respectively.

The successive vapour phase condensation of ethanol and 1-butanol (via Guerbet reaction) in a flow reactor under atmospheric pressure was studied over catalytic Mg-Al oxide compositions. Wherein the vapour phase condensation of 1-butanol to 2-ethyl-1-hexanol in flow has been investigated for the first time. The acid/base capacity ratio, which is determined by the Mg/Al ratio, is an important characteristic for the activity and selectivity of Mg-Al oxide catalysts in the abovementioned processes. The carbon chain length of the reacting alcohols, an arrangement of surface active sites and other steric factors also have an impact on Guerbet condensation in the vapour phase. High productivity of Mg-Al oxide system to the Guerbet alcohols: 1-butanol – 25 g/(Lcat·h), 2-ethyl-1-hexanol – 19 g/(Lcat·h), has been achieved. The results have shown a prospect of successive conversion realization: 1) ethanol → 1-butanol; 2) 1-butanol → 2-ethyl-1-hexanol for the production of 2-ethyl-1-hexanol from ethanol.

The nature of active acid sites of zeolite H-BEA with different Si/Al ratios (15-407) in liquid phase etherification of isobutylene with ethanol in a continuous flow reactor in the temperature range 80-180 °C has been explored. We describe and discuss data concerning the strength and concentration of acid sites of H-BEA obtained by techniques of stepwise (quasi-equilibrium) thermal desorption of ammonia, X-ray diffraction, low-Temperature adsorption of nitrogen, FTIR spectroscopy of adsorbed pyridine and solid-state 27Al MAS NMR. The average values of the adsorption energy of NH3 on H-BEA were experimentally determined as 63.7; 91.3 and 121.9 mmol g-1 (weak, medium, and strong, respectively). In agreement with this, a correlation between the rate of ethyl-Tert-butyl ether synthesis and the concentration of weak acid sites (ENH3 = 61.6-68.9 kJ mol-1) has been observed. It was concluded that the active sites of H-BEA for this reaction are Br?nsted hydroxyls representing internal silanol groups associated with octahedrally coordinated aluminum in the second coordination sphere.

Some metal-organic frameworks (MOFs) incorporate nodes that are metal oxide clusters such as Zr6O8. Vacancies on the node surfaces, accidental or by design, act as catalytic sites. Here, we report elucidation of the chemistry of Zr6O8 nodes in the MOFs UiO-66 and UiO-67 having used infrared and nuclear magnetic resonance spectroscopies to determine the ligands on the node surfaces originating from the solvents and modifiers used in the syntheses and having elucidated the catalytic properties of the nodes for ethanol dehydration, which takes place selectively to make diethyl ether but not ethylene at 473-523 K. Density functional theory calculations show that the key to the selective catalysis is the breaking of node-linker bonds (or the accidental adjacency of open/defect sites) that allows catalytically fruitful bonding of the reactant ethanol to neighboring sites on the nodes, facilitating the bimolecular ether formation through an SN2 mechanism.

Hierarchical zeolites are known to offer fast mass transfer along with size and shape selectivity compared to their conventional micron-sized zeolite counterparts. We report here the successful synthesis and characterization of a hierarchical ZSM-48 zeolite (?MRE-type structure) using a specific gemini-type surfactant that acts as dual functions template to generate at the same time micropores and mesopores. The Si/Al molar ratio of the starting gel seems to influence the nature of the obtained zeolitic phase. Pure hierarchical ZSM-48 zeolites were only obtained at a high Si/Al molar ratio of the starting gel (Si/Al = 31 to 50). The catalytic properties of these acidic catalysts were then tested in ethanol transformation into hydrocarbons.

Li1 + xHf2–xInx(PO4)3 (x = 0, 0.05, 0.1) materials have been prepared by solid-state reactions and characterized by X-ray diffraction, low-temperature nitrogen adsorption measurements, and scanning electron microscopy. The materials consist of NASICON-type lithium hafnium double phosphates with a hexagonal structure. Milling in a planetary mill has been found to increase the specific surface area of the Li1 + xHf2–xInx(PO4)3 materials by almost one order of magnitude (from 1.5 to 13 m2/g in the case of LiHf2(PO4)3). The materials with a larger surface area exhibit catalytic activity for ethanol dehydration reactions and are less active for ethanol dehydrogenation. Ethanol conversion predominantly yields diethyl ether at low temperatures and ethylene at higher temperatures. The diethyl ether selectivity of the catalytic processes reaches 85% at 350°C, with 60% conversion, and the ethylene selectivity reaches 96% at 510°C, with 100% conversion. Indium doping raises the high-temperature acetaldehyde selectivity from 4 to 8% and leads to the formation of C4 hydrocarbons as reaction products. C4 selectivity reaches 15 and 17% in the case of the Li1.05Hf1.95In0.05(PO4)3 and Li1.1Hf1.9In0.1(PO4)3 materials, respectively (420°C, 97 and 92% conversion, respectively).

The condensation of ethanol to 1-butanol in the presence of different catalyst systems based on a Pd dehydrogenating/hydrogenating component and magnesium hydroxide-derived materials as basic ingredient was studied in a fixed-bed reactor. The metal was incorporated by wetness impregnation, and the resulting material was then reduced in situ with hydrogen at 573 K for 1 h before reaction. The bifunctional catalysts were tested in a fixed-bed reactor operated in the gas phase at 503 K and 50 bar with a stream of helium and ethanol. A bifunctional catalyst supported on a synthetic composite based on Mg and high surface area graphite (HSAG) was also studied. Improved catalytic performance in terms of selectivity towards 1-butanol and stability was shown by the Pd catalyst supported on the Mg–HSAG composite after thermal treatment in helium at 723 K, presumably due to the compromise between two parameters: adequate size of the Pd nanoparticles and the concentration of strongly basic sites. The results indicate that the optimal density of strongly basic sites is a key aspect in designing superior bifunctional heterogeneous catalyst systems for the condensation of ethanol to 1-butanol.

In an effort to verify a previous striking report that ethanol could be oxidized selectively to ethylene oxide, ethanol oxidation on Ag, Cu, or Au nanoparticles supported on Li2O/γ-Al2O3 or γ-Al2O3 was examined between 100 and 400 °C. Ag and Cu catalysts were found to be highly selective to acetaldehyde (>95% on Ag below 325 °C and on Cu below 250 °C). On Au, selectivities to acetaldehyde were lower, with higher selectivity to ethyl acetate and acetic acid. No ethylene oxide was observed under any conditions. Our results, including selectivity variations among these metals, are consistent with previous studies of ethanol oxidation over coinage metals supported on γ-Al2O3, with no changes in primary product identity and minor changes in selectivity upon addition of Li2O. Unfortunately, these results are in direct contradiction to previous work reporting the desirable direct conversion of ethanol to ethylene oxide on Ag, Cu, and Au on Li2O/γ-Al2O3.

A process for producing 1,3-butadiene (BD) from ethanol in a single step by s7 passing a mixture containing ethanol in a gas phase over a multifunctional catalyst having a transition metal dispersion of at least 30% on a silica metal oxide support. In some examples the multifunctional catalyst comprises a silica metal oxide having a surface area of at least 200 m?2/g. The multifunctional catalyst can include a transition metal oxide, a silica metal oxide made from a high purity silica gel, mesoporous silica and fumed silica, such as high purity SBA16, SBA15, or Davisil grade 646.

In– Nb– Mo-doped lithium complex phosphates and HZr2(PO4)3 with NASICON-type structure were synthesized in this paper. Particle size distribution lies between 50 and 300 nm. The obtained samples were characterized by X-ray diffraction analysis, scanning electron microscopy and X-ray microanalysis. Investigation of the catalytic properties of synthesized compounds in the C1–C2 alcohols conversions showed that heterovalent doping has a determining effect on the obtained catalysts’ activity and selectivity. It is shown that the thermodynamic factors and the dopant ability to change the degree of oxidation and acid function of the catalysts play a key role in methanol and ethanol conversion. A number of catalysts show the high activity and selectivity of the formation of dimethyl and diethyl ethers and ethylene. High selectivity for C4 hydrocarbons is achieved by LiZr2(PO4)3 and Li0.5Zr2P2.5Mo0.5O12 catalysts (64 and 49%, respectively) in the case of ethanol conversion.

Catalytic synthesis of 1,3-butadiene from dimethyl ether (DME) has been carried out for the first time. It has been established that 1,3-butadiene forms via three possible routes of reactions between DME conversion products: by reaction of propylene with

A deactivation study on the ethanol/acetaldehyde conversion to 1,3-butadiene over a ZnO promoted ZrO2-SiO2 catalyst prepared by a sol-gel method was performed. The samples were characterized by N2 adsorption-desorption isotherms, scanning electron microscopy (SEM), NH3 temperature programmed desorption (NH3-TPD), X-ray powder diffraction characterization (XRD), thermogravimetric analyses (TGA), Fourier transform infrared resonance (FT-IR), 13C magic-angle spinning nuclear magnetic resonance (13C NMR) and X-ray photoelectron spectroscopy (XPS). The pore structure characteristics and surface acidity of Zn0.5-Zr-Si catalysts were largely decreased with time-on-stream and no crystal structure was formed in the used catalyst, indicating that the deactivation was caused by carbon deposition. Two main types of carbon deposition were formed, namely low-temperature carbon deposition with the oxidation temperature of around 400 °C and high-temperature carbon deposition with the oxidation temperature of 526 °C. The carbon species were mainly composed of graphitized carbon, amorphous carbon, carbon in C-O bonds and carbonyls. The deactivated catalyst could be regenerated by a simple oxidation process in air. Adding a certain amount of water into the feed had a positive effect on reducing the carbon deposition.

Synthesis of benzyl alkyl ethers was performed in high yields by intermolecular dehydration of benzyl and primary, secondary, tertiary alcohols under the effect of copper containing catalysts. The formation of benzyl alkyl ethers occurs with participation of benzyl cation.

Carbon nanomaterials with the structure of graphene and different compositions of the surface groups are used as catalysts for the conversion of С2–С4 aliphatic alcohols. The conversions of ethanol, propanol- 1, propanol-2, butanol-1, butanol-2, and tert-butanol on carbon nanotubes, nanoflakes, and nanoflakes doped with nitrogen are investigated. Oxidized and nonoxidized multiwalled carbon nanotubes, nanoflakes, and nanoflakes doped with nitrogen are synthesized. X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning and transmission electronic microscopies, Brunauer–Emmett–Teller method, derivatographic analyses, and the pulsed microcatalytic method are used to characterize comprehensively the prepared catalysts. It was established that all of the investigated carbon nanomaterials (with the exception of nondoped carbon nanoflakes) are bifunctional catalysts for the conversion of aliphatic alcohols, and promote dehydration reactions with the formation of olefins and dehydrogenation reactions with the formation of aldehydes or ketones. Nanoflakes doped with nitrogen are inert with respect to secondary alcohols and tert-butanol. The role of oxygen-containing and nitrogen-containing surface groups, and of the geometrical structure of the carbon matrix of graphene nanocarbon materials in the catalytic conversion of aliphatic alcohols, is revealed. Characteristics of the conversion of aliphatic alcohols that are associated with their structure are identified.